1. Field of the Invention
The present invention generally relates to an enclosure having an access cover and more specifically relates to an enclosure for a portable machine, the enclosure including a resilient cover which provides access to a portion of the portable machine.
2. Description of the Prior Art
Portable machines, such as portable air compressors, are typically mounted upon a trailer and include a protective enclosure or cover secured over the top of the air compressor. The trailer may include wheels and a tow bar so that the trailer may be easily moved between job sites. Upon arriving at a job site, the air compressor may be operated to provide compressed air for pneumatic tools and other devices.
U.S. Pat. No. 5,518,262 discloses a trailer for a portable air compressor including a lower frame having two wheels rotatably mounted thereto and a towing assembly mounted to a front end of the lower frame for towing the trailer between job sites. The air compressor is mounted to the lower portion of the trailer. The trailer typically includes a cover secured atop the lower frame, the cover having one or move hatches which may be selectively opened for gaining access to the air compressor. The cover generally protects the air compressor and other internal components, such as the engine, control panel and gauges, etc. . . . , necessary for operating the compressor. The cover also attenuates and/or muffles noises produced during operation of the compressor. The trailer disclosed in the '262 patent has proven to be extremely reliable and serviceable due, in part, to the heavy-duty steel used to construct the trailer.
An operator of a portable air compressor must frequently interface with one or more control panels. The control panels may contain switches for starting the air compressor and regulating the flow of compressed air. The control panels may also include gauges for monitoring the performance of the air compressor. The control panels are usually protected by covers which shield the relatively delicate switches and instruments provided on the control panels. Operators frequently have difficulty opening the control panel access covers because the covers are generally designed to fit flush with the outside surfaces of the trailer enclosure and an operator wearing heavy gloves cannot easily grasp an edge of the cover. This is particularly true if the enclosure for the air compressor is made of polymer materials, such as the enclosure disclosed in commonly assigned, co-pending U.S. patent application Ser. No. 09/175,268, the disclosure of which is hereby incorporated by reference herein. In response, attempts have been made to provide such polymer covers with apertures or handles for lifting the cover. One design was directed to cutting or molding an aperture either in the cover itself or in an area of the enclosure adjacent the cover. This design has proven effective for enabling operators to open the cover, however, the aperture provides a weak point at which an intruder may breach the integrity of the enclosure and gain unauthorized access to the interior region thereof. Other designs are directed to molding protrusions, such as handles, on the outer surface of the cover. Such designs are generally ineffective because the shape of the cover and the limitations inherent in molding processes limit the size of the protrusion. In addition, molded handles protrude from the cover and are likely to break off from the cover during extended use or a high-impact collision.
Thus, there is a need for an improved enclosure having an access cover which is durable, secure and capable of being readily opened. In particular there is a need for a polymer cover for an enclosure which automatically springs to the open position when an operator desires to gain access to the interior region of the enclosure. The cover should be resilient and durable so that the cover does not fatigue and so that the cover may be repeatedly opened and closed during long-term use of the enclosure.